Differential emergency/park electric brake system

ABSTRACT

A system, apparatus and method provide emergency differential braking for effecting braked steering of an aircraft. A brake input device is provided that not only allows for emergency and parking brake functions, but also enables differential braking. The brake input device (e.g., a parking and/or emergency brake lever, pedal, handle, etc.) can be used in a brake system including a brake system control unit (BSCU), one or more electro-mechanical actuator controllers (EMACs) and a brake assembly including one or more electrical actuators. Each EMAC is electrically coupled to one or more of the actuators so as to provide electrical power for driving the actuators. Each EMAC is also communicatively coupled to the BSCU so as to receive braking data therefrom. In an emergency, the input device sends braking signals directly to the brake actuators.

FIELD OF THE INVENTION

The present invention relates generally to brakes and, moreparticularly, to brake controls for providing parking and emergencybraking functions in an aircraft.

BACKGROUND

Aircraft, much like other vehicles, incorporate an emergency brakingsystem that activates the brakes for long term parking, and foremergency stopping when the principal brake system fails. Such emergencybrake systems may be electrically or hydraulically operated, and arewell known to those having ordinary skill in the art.

In electrically operated emergency brake systems, an emergency brakecommand signal (in the form of an analog or digital signal) is generatedby an emergency brake lever or handle, and this signal is provided to abrake system control unit (BSCU). The BSCU, based on the signal,commands an electro-mechanical actuator controller (EMAC) to power anactuator. The EMAC, in response to the command from the BSCU, provideselectrical power to an actuator of a brake assembly so as to effect abraking force.

Additionally, electrically operated brake systems also include aseparate emergency brake control box. The emergency brake control box isconfigured to control the brake actuators during failure of the primarybrake system (e.g., during failure of the BSCU). Typically, such systemsare designed to activate all brakes the same amount so as to bring theaircraft to a stop.

SUMMARY OF INVENTION

A brake input device for an emergency brake system is provided that notonly allows for emergency and parking brake functions, but also allowsdifferential braking to effect braked steering of an aircraft. Thisallows the pilot to not only stop the plane in an emergency, but also tosteer the plane with the brakes during an emergency stop. Morespecifically, the brake input device (e.g., a parking and/or emergencybrake lever, pedal, handle, etc.) can be used in a brake systemincluding a brake system control unit (BSCU), one or moreelectro-mechanical actuator controllers (EMACs) and a brake assemblyincluding one or more electrical actuators. Each EMAC is electricallycoupled to one or more of the actuators so as to provide electricalpower for driving the actuators. Each EMAC is also communicativelycoupled to the BSCU so as to receive braking data therefrom.

Each EMAC may include a switch or the like for selecting a signal to beprovided to the EMAC's servo compensation network and driver circuits.The switch is controlled via a braking mode signal (normal orpark/emergency) generated based on the brake input device. The output ofthe switch is coupled to an input of the EMAC's servo compensationnetwork and actuator driver circuits so as to select the signal used bythe servo compensation network and driver circuits for controlling theactuators.

For normal brake operation, the BSCU generates a brake force signalcorresponding to a desired brake force, and provides the brake forcesignal to each EMAC. Each EMAC's processor, based on the brake forcesignal from the BSCU, generates a brake control signal for the servocompensation network and actuator driver. During normal brake mode, theswitch selects the signal generated by the EMAC's processor and providesthis signal to the servo compensation network and driver circuits. Thus,overall brake control during normal braking is provided via the BSCU andthe EMAC's processors.

For parking and/or emergency braking/steering operation, the brake modesignal provided to each EMAC is indicative of park/emergency/steeringmode. Based on this mode, the switch routes the brake command signal(s)as generated by the brake input device directly to the EMAC's servocompensation network and actuator drivers. The servo compensationnetwork and drivers then control the actuators so as to effect a brakingforce. Thus, during parking and emergency braking/steering, both theBSCU and the EMAC's processor are bypassed, and brake control isdirectly provided by the brake input device (e.g., from the brakehandle). Such architecture is advantageous as it eliminates the need fora separate (or isolated) emergency control box to command the EMACs inthe event of failure of the primary braking system.

According to one aspect of the invention, an emergency brake inputdevice for providing emergency braking signals to at least two brakeactuators associated with respective left hand and right hand brakeassemblies of a vehicle comprises an input member movable in a firstdirection corresponding to a braking magnitude and movable in a seconddirection corresponding to a relative distribution of the brakingmagnitude between first and second brake signals for the control of theat least two brake actuators. The first and second brake signals can bemodulated by a pilot during emergency braking so as to applydifferential braking to separate wheels of an aircraft.

More particularly, the input member can be movable linearly betweenfirst and second positions corresponding to minimum and maximum brakingmagnitudes, with the position of the handle being indicative of adesired magnitude of braking. The input member can be rotatable aboutits central axis with an angular position of the input member beingindicative of a desired distribution of the braking magnitude betweenthe first and second signals. For example, the input member can includea handle that is both slideable linearly and rotatable. At least onesensor can be provided for sensing a position of the input member andgenerating the brake signals in response thereto. The input device canalso include a parking brake lock for locking the input member in aparking brake position, which may correspond to a maximum magnitude ofbraking. A parking brake sensor for sensing when the input device is ina parking brake mode and for generating a signal in response thereto canalso b provided.

In accordance with another aspect, an aircraft braking system comprisesat least one brake assembly for braking a wheel of an aircraft, thebraking assembly including at least one actuator for effecting a brakingaction in response to a braking signal provided thereto, and a brakeinput device as set forth above for providing the braking signal to theactuator.

In accordance with another aspect, an emergency brake system comprisesat least two brake assemblies having actuators for braking respectivewheels of an aircraft, and an emergency brake input device for providingemergency braking signals to each actuator. The input device has firstand second input members for generating first and second brake signalsfor the control of the at least two brake assemblies, the input memberseach being movable between a first position corresponding to a minimummagnitude of braking and a second position corresponding to a maximummagnitude of braking. The first and second brake signals can bemodulated by a pilot during emergency braking so as to applydifferential braking to separate wheels of an aircraft.

More particularly, the first and second input members can be pedals. Atleast one sensor can be provided for sensing a position of an inputmember and generating a brake signal in response thereto. A parkingbrake lock can be provided for locking the input members of the inputdevice in a parking brake position, which position may correspond to amaximum magnitude of braking. The parking brake lock can include a latchthat maintains the first and second input members in the parking brakeposition. A parking brake sensor for sensing when the input device is ina parking brake mode and for generating a signal in response thereto canalso be provided.

According to another aspect, a method of applying differential brakingof wheels of an aircraft during emergency braking comprises generating afirst brake signal indicative of a braking force to be applied to afirst wheel by a first brake assembly, generating a second brake signalindicative of a braking force to be applied to a second wheel by asecond brake assembly, and feeding the first and second signals to thefirst and second brake assemblies to effect braking of respective wheelsin response to the respective first and second signals.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrativeembodiments of the invention. These embodiments are indicative, however,of but a few of the various ways in which the principles of theinvention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simple schematic diagram illustrating an exemplaryarchitecture for controlling an aircraft braking system in accordancewith the present invention.

FIG. 2 is a diagrammatic illustration of an exemplary multi-actuatorcomputer controlled brake actuation system.

FIG. 3 is a diagrammatic illustration of a brake actuator and associatedservo amplifier employed in the system of FIG. 2.

FIGS. 4A and 4B are schematic diagrams illustrating an exemplary brakeinput device in accordance with the invention.

FIGS. 5A-5D are schematic diagrams illustrating another exemplary brakeinput device in accordance with the invention in various modes ofoperation.

FIG. 6 is a schematic diagram illustrating a side view of the exemplarybrake input device of FIGS. 5A-5D.

FIG. 7 is a schematic diagram illustrating a top view of the exemplarybrake input device of FIGS. 5A-5D with a sensor arrangement fordetecting activation of the device.

FIGS. 8A-8C are schematic diagrams illustrating another exemplary brakeinput device in accordance with the invention in various modes ofoperation.

FIG. 9 is another schematic drawing of the brake input device of FIGS.8A-8C.

FIG. 10 is a schematic side view of another exemplary brake inputdevice.

FIG. 11 is a schematic top view of the brake input device of FIG. 10.

FIG. 12 is a perspective view of another exemplary brake input device inaccordance with the invention.

FIG. 13 is a schematic top view of the brake input device of FIG. 12.

FIG. 14 is a schematic side view another exemplary brake input device.

FIG. 15 is a schematic plan view of the exemplary brake input device ofFIG. 14 in various positions.

FIG. 16 is a graph illustrating the brake command level generated by thebrake input device of FIGS. 14-15 in various positions.

FIG. 17 is a functional diagram of the brake input device of FIG. 10.

DETAILED DESCRIPTION

The principles of the invention will now be described with reference tothe drawings. Because the invention was conceived and developed for usein an aircraft braking system, it will be herein described chiefly inthis context. However, the principles of the invention in their broaderaspects can be adapted braking systems in other types of vehicles.Moreover, the following discussion of an exemplary multi-actuatorcomputer controlled brake actuation system is given for the sake ofillustration and not by way of limitation, except as defined in theclaims included at the end of this specification. Accordingly, onlygeneral operational details and features of such system will bedescribed so as not to obscure the teachings of the present inventionwith details that may vary from one particular application to another.

Referring initially to FIG. 1, there is shown an exemplary electricalbrake system 10 having architecture in accordance with the presentinvention. The exemplary electrical brake system includes a brake systemcontrol unit (BSCU) 12 configured to carryout braking operations of theaircraft as is conventional. The BSCU 12 is configured to receivevarious operator inputs, such as left and right pilot brake pedalsignals from left and right pilot brake pedals 14 l and 14 r, and leftand right co-pilot brake pedal signals from left and right co-pilotbrake pedals 16 l and 16 r. The brake pedal signals can be generated,for example, via LVDTs (linear variable differential transformers—notshown) operatively coupled to the respective pedals. As the pedals aredepressed, each LVDT generates a voltage signal corresponding to thedegree of pedal deflection, and this voltage signal can be provided tothe BSCU 12 as is conventional. As will be appreciated, other knownmethods for generating the brake pedal signals may also be employed,including encoders, potentiometers, or the like.

The BSCU 12 may also receive other operator inputs, such as data from anautobrake switch 18 for configuring autobrake logic. The autobrakeswitch 18 may include several settings, such as an enable/disable input,an auto braking level input (e.g., low, medium, high) and a rejectedtake off (RTO) input (e.g., for enabling or disabling RTOfunctionality). The BSCU 12 may also receive other aircraft data 20,such as discrete data (e.g., sensor data such as weight-on-wheels,landing gear up/down, etc.), analog data (e.g., force data, temperaturedata, etc.), serial data, etc. as is conventional.

The BSCU 12 is communicatively coupled to one or more electro-mechanicalactuator controllers (EMACs) 24, wherein the BSCU 12 provides a brakeforce signal to the respective EMACs during normal braking operations.Preferably, the coupling is via a serial communication link, althoughdata also can be exchanged via discrete and/or analog connections. TheBSCU 12 is configured to derive the brake force signal based on brakedata generated by the pedals 14 l, 14 r, 16 l, 16 r, and/or autobrakeand antiskid control.

A brake input device 22, preferably a combination parkingbrake/emergency brake device (e.g., a handle, lever, pedal, or thelike), provides a brake command signal to each EMAC 24. The brakecommand signal can be generated using known techniques, such as an LVDTas described above with respect to the brake pedals 14 l, 14 r, 16 l, 16r, or via an encoder or potentiometer configured to provide datacorresponding deflection or rotation of the brake input device 22. Aswill be appreciated, other known methods of generating the brake commandsignal may also be employed. Preferably, the brake input device includesa mode selector to indicate when normal or parking/emergency braking isdesired. For example, the brake input device 22 may include contactsthat are open when the brake input device is in a first position (e.g.,rotated to the left or pushed inward) and closed when the brake inputdevice is in a second position (e.g., rotated to the right or pulledoutward). Alternatively, the brake mode selector may be separate fromthe brake input device 22. The brake input device 22 can also provideseparate braking signals for respective left and right side brakes aswill be described in more detail below. Further details regardingvarious brake input devices are provided below with respect to FIGS. 4Athrough 9.

The EMACs 24 are electrically coupled to one or more actuators 26 of abrake assembly 28, wherein each brake assembly 28 includes the one ormore actuators 26, corresponding rams 30 operatively coupled to eachactuator 26, and a brake-disk stack 30 having a plurality of rotorscoupled for rotation with a wheel 34 and stators rotationally fixed withrespect to the wheel 34. Each actuator 26 and ram 30 are configured forforceful engagement with the brake-disk stack 30 so as to provide abrake force to a corresponding wheel 34. Wheel speed sensors 36 providewheel speed data to the BSCU 12 for implementing anti-skid and autobrakefunctions as is conventional.

As noted above, each EMAC 24 receives the brake force signal from theBSCU 12. In addition to the brake force signal, each EMAC 24 isconfigured to receive the brake command signal from the brake inputdevice 22, and the brake mode signal indicative of whether normal brakeoperation or park/emergency brake operation is desired. Based on thebrake mode signal, each EMAC 24 selects a signal corresponding to thebrake force signal provided by the BSCU 12 or the brake command signalprovided by the brake input device 22 and, based on the signal, controlsthe actuators to effect a braking force. Further details regarding EMACoperation are discussed below with respect to FIGS. 2 and 3.

FIG. 2 diagrammatically illustrates an exemplary multi-actuator computercontrolled electrical brake actuation system 10′ to which the principlesof the invention may be applied. The major functions of the system 10′are performed by an EMAC controller 40 and a brake actuator assembly 42.The brake actuator assembly 42 may be mounted in a conventional manneron a wheel and brake assembly 44 to apply and release braking force on arotatable wheel 34 of such wheel and brake assembly. Wheel speed data isprovided to the controller 40 via a wheel speed sensor 36 coupled toeach wheel 34.

In the illustrated exemplary system 10′, the brake actuator assembly 42includes at least one and preferably a plurality of actuators 26, suchas electro-mechanical actuators (EMAs) 26. The EMAC controller 40includes a corresponding number of independent servo amplifiers 46, amicro-processor 48 with associated peripherals, and a data input/output(I/O) circuitry 50. As depicted, plural (for example, four) independent,linear electro-mechanical servo loops operate in a position mode, i.e.,the linear position of each actuator is a function of an analog inputvoltage (or digital equivalent for a digital signal processor) appliedto a position command input.

As noted above, the brake input device 22, via signal generator 22 a,generates the brake command signal, which is provided to each EMAC(e.g., to each amplifier 46 of the EMAC). Also provided to eachamplifier is a brake mode input, which is generated via switch 22 b.During normal braking operations, switch 22 b is closed, and brakecontrol is performed via the BSCU 12 and EMAC controller 40. However,during park/emergency braking operations, switch 22 b is open, and eachamplifier 46 uses the braking command as provided by the brake inputdevice 22, thereby bypassing the BSCU 12 and EMAC controller 40. Thus,each amplifier can include a switching means for selecting between thedata generated by the BSCU 12 and processor 48, or the actual dataprovide by the brake input device 22.

In FIG. 3, a representative electro-mechanical brake actuator 26 andassociated servo amplifier 46 are illustrated in greater detail. Thebrake actuator 26 includes an electric servo motor 52, gear train 54,and a reciprocating output ram 30. The brake actuator has associatedtherewith an output ram position sensor 56 which provides for actuatorposition feedback as depicted, and a force sensor 58 that provides dataindicative of a force applied by the brake actuator on the brake-diskstack. Although not shown, the brake actuator 26 also has associatedtherewith a motor tachometer to provide for velocity feedback.

The servo amplifier 46 includes servo loop compensation network andamplifiers 60, and a DC motor driver 62 with associated control logicand current control circuitry. More particularly, the servo amplifier 46may include an inner motor current control servo loop 64, anintermediate motor velocity servo loop 66, and a ram position servo loop68. Force feedback data 69 may be provided to the BSCU for control ofactual applied force. Each loop may be compensated to obtain desiredperformance in terms of bandwidth, and to provide for uniform dynamicresponse of all brake actuators 26. In addition, the servo amplifier 46includes means for controlling motor current and therefore the outputforce of the brake actuator in response to a force control input. Theforce control input may be an analog input signal that controls motorcurrent level while the aforesaid position command input controlsactuator displacement. As will be appreciated, the analog input signalsmay be replaced by digital input signals if a digital signal processoris used in the servo amplifier for actuator control.

A switch 65 provides an input to the servo loop compensation network 60.Preferably, switch 65 is an electronic or software switch. However, amechanical switch may be employed depending on the configuration of theEMAC 24. The switch 65 includes a first input 11 configured to receivethe brake control signal from the EMAC controller 40 (which effectivelyis derived from the pedals 14 l, 14 r, 16 l, 16 r and/orautobrake/antiskid logic from the BSCU 12), and a second input I2configured to receive the brake command signal from the brake inputdevice 22. A select input SE of switch 65 is coupled to the mode switch22 a, and an output of switch 65 is coupled to the servo loopcompensation network as noted above. Based on the particular brakingmode as indicated by the mode switch 22 b, the switch 65 will provideeither the brake control signal (from the EMAC controller 40) or thebrake command signal (from the brake input device 22) to the servo loopcompensation network 60. Although not shown, scaling logic may beincluded in the EMAC to properly scale the brake command signal for usewith the EMAC circuitry. Further, while the switch is shown as part ofthe EMAC, it is possible for the switch to be separate from the EMAC 24.

During normal braking, the select input SE is true, and the switch 65connects the first input 11 to the switch output, thereby coupling thebrake control signal from the EMAC controller 40 to the servo loopcompensation network 60 (and thus the motor driver 62). Accordingly, thedisplacement of each actuator 26 is controlled by the electroniccontroller 40 (FIG. 2) and the BSCU 12. The micro-processor 48 of thecontroller 40 provides brake control algorithm processing, temporarydata storage in RAM, program memory storage, non-volatile data storage,and control of the servo amplifiers 46 via the input/output circuitry50. The input/output circuitry 50 provides for digital-to-analog dataconversion, generating the analog position commands and the analog motorcurrent control commands to the four actuators, analog-to-digital dataconversion to monitor the actuator position sense and motor currentfeedback signals, and signal discretes for auxiliary functions such asmotor brake control. Although micro-processors are utilized in theillustrated preferred embodiment, processing could be done analog asopposed to digital, or intermixed with digital processing as may bedesired.

During park/emergency braking operations, both the BSCU 12 andcontroller 40 are bypassed, and the displacement of each actuator 26 isdirectly controlled by brake input device 22. More specifically, whenthe brake mode corresponds to park/emergency braking, the select inputSE is false, and the switch 65 connects the second input I2 to theswitch output, thereby directly coupling the brake command signal fromthe brake input device 22 to the servo loop compensation network 60.Thus, in the event of primary brake system failure, park/emergencybraking can be provided via the each EMAC, without the need for anemergency control unit. As will be appreciated, the brake input device22 can provide brake signals to respective left and right brakeassemblies, for example, for implementing braked steering. Furtherdetails of the brake system are set forth in commonly-assigned U.S.patent application Ser. No. 12/429,303 filed on Apr. 24, 2009 titled“ELECTRIC BRAKE ARCHITECTURE WITH DISSIMILAR EMERGENCY BRAKING PATH,”which is hereby incorporated by reference herein in its entirety.

Referring now to FIGS. 4A and 4B, a brake input device 22 isschematically shown from a top view (FIG. 4A) and a side view (FIG. 4B).The exemplary brake input device 22 includes a handle 70 configured formovement along a channel or guide 72. Operatively coupled to the handle70 is a signal generator 22 a, such as a potentiometer 22 a, whereinmovement of the handle 70 along the channel 72 causes a correspondingdeflection of a wiper arm 23 a of the potentiometer. By applying avoltage across the outer terminals 23 b and 23 c of the potentiometer 22a, a brake command signal can be generated at the wiper arm terminal 23d that corresponds to the position of the handle within the channel (andthus the desired amount of braking).

It is noted that reference to a potentiometer is merely exemplary, andother devices, such as an LVDT, encoder, etc. may be used in place ofthe potentiometer to derive the brake command signal. Although not shownin FIG. 4A, the terminals of the potentiometer 22 a are electricallycoupled to the EMAC 24 so as to provide the brake command signalthereto.

With further reference to FIG. 4B, a simple side schematic view of theexemplary brake input device 22 is shown. The handle 70, in addition tobeing operatively coupled to the signal generator 22 a, is alsooperatively coupled to switch 22 b. Preferably, handle 70 is amaintained push-pull handle such that it can be maintained in an outposition (pull) or an in position (push). When in the “out/pull”position, switch 22 b is in an electrically closed state, and while inthe “in/push” position, switch 22 b is in an electrically open state.The “out/pull” position can correspond to normal braking mode (i.e.,brake control via the BSCU 12), while the “in/push” position cancorrespond to park/emergency mode. Switch 22 b is electrically coupledto switch 65 so as to provide an indication of the current braking mode(normal or park/emergency).

In another embodiment, the brake input device can comprise a rotatablehandle (as opposed to a push/pull device). In this embodiment, rotationof the handle in one direction (e.g., left) may correspond to normalbrake mode, and rotation of the handle in another direction (e.g.,right) can correspond to park/emergency brake operation.

Accordingly, the brake input device 22 can provide both a park/emergencybrake reference, and a mode indicator that can be used to configure thebrake system's mode of operation. This is advantageous, as the pilotneed only manipulate a single controller for park/emergency brakeoperation.

Turning to FIGS. 5A-5D and 6, and initially to FIGS. 5A and 6, a brakeinput device 82 is shown that provides functionality similar to thebrake input device 22 described above, but also facilitates differentialbraking to effect braked steering during emergency braking. The brakeinput device 82 is similar to the device 22 in both form and functionwith the exception of the handle 70, which is rotatable about itscentral axis to control an amount of braking applied to separate brakeassemblies, for example left and right brake assemblies.

Accordingly, brake input device 82 includes handle 70 mounted on guide72 for both sliding and rotating movement, and a pair of side buttons 84for permitting emergency braking and also for locking the handle 70 inthe park position, as will be described in more detail below. Similar toinput device 22 described above, sliding the handle 70 forward producesan increasing brake signal. In this embodiment, however, rotation of thehandle 70 produces respective left and right brake signals that can befed directly to each EMAC to effect differential braking. A directionalindicator 86 indicates the direction in which the aircraft will besteered relative to the forward direction (e.g., with respect to thelongitudinal axis of the guide 72).

More specifically, and with further reference to the remaining FIGS.5B-5D, the input device 82 is shown in various positions correspondingto various braking actions. In FIG. 5A the handle 70 is locked in theaft position corresponding to no braking activity. The side buttons 84are not depressed and serve to hold or otherwise lock the handle in theillustrated position to avoid inadvertent brake actuation. FIG. 6illustrates a schematical side view of the brake input device 82 in theposition of FIG. 5A

In FIG. 5B, the side buttons 84 have been depressed and the handle 70has been moved to a position corresponding to moderate emergencybraking. The indicator 86 is pointing straight forward thus indicatingthat the brake input device 82 is providing identical (or nearlyidentical) first and second signals to the brake actuators for actuatingrespective left and right brake assemblies such that the aircraft brakesin a relatively straight line.

In FIG. 5C, the handle 70 has been rotated counterclockwise such that itis now pointing to the left of the longitudinal axis of the guide 72.This position corresponds to differential (steered) braking wherein theaircraft tends to rotate left during emergency braking. As will beappreciated, the brake input device 82 can be configured to generaterespective output signals for the left and right brake assemblies inresponse to rotation of the handle 70. For example, when rotated to theleft, the left hand brake assembly or assemblies would be activated to agreater extent than the right hand brake assembly or assemblies causingthe aircraft to rotate towards the left. Conversely, when the handle isrotated to the right (not shown), the right side brake assembly orassemblies would be activated to a greater extent than the left sidebrake assembly or assemblies causing the aircraft to rotate towards theright.

In FIG. 5D, the handle 70 is in its forward-most position correspondingto full braking and/or parking brake mode. In this instance, the sidebuttons 84 have returned outward indicating that the handle 70 is lockedin the parking brake position. Once in this position and with the sidebuttons 84 locked, the brake input device 82 generates a signalindicative of the parking brake being applied as described previously.

Accordingly, the brake input device 82 of FIGS. 5A-5D facilitates bothdifferential emergency braking for steering the aircraft during anemergency stop, as well as a parking brake function. The exemplarydevice 82 is intuitive since braking action is applied by sliding thehandle 70 forward (much like depressing a pedal), while differentialbraking is achieved by rotating the handle 70 in the direction the pilotdesires to steer the plane. Of course, the handle 70 could be configuredto be pulled rather than pushed to generate the braking signal. As willbe appreciated, the brake input device 82 need not have a particularform or shape. For example, the handle 70 can be made to look like thewheels of an aircrafts, while the side buttons 84 can be made to looklike wheel chocks. In the illustrated embodiment, the input device isbiased towards the position shown in FIG. 5A (e.g., no braking and nodifferential braking).

Further, the side buttons 84 can be configured to work in a variety ofways. For example they may restrict initial movement of the handle 70from the position of FIG. 5A until depressed. The side buttons may thenremain in the depressed state as the handle is slid fore and aft by thepilot, only to return to the locked position upon return of the handle70 to the position of FIG. 5A, or upon engagement of the parking brake(e.g., by pushing the handle 70 all the way forward). The side buttons84 may then retain the handle 70 in the parking brake position.

Turning to FIG. 7, further details of the brake input device 82 areillustrated. The handle 70 is supported for sliding and rotationalmovement on the guide (not shown in FIG. 7) and is coupled to a pair ofcog belts 90 a and 90 b. Each cog belt 90 a and 90 b passes around arespective idler pulley 92 a and 92 b and a respective angulardisplacement sensor 94 a and 94 b, thus coupling the handle 70 to thesensors. Idler wheels 96 are fixed for sliding movement along with thehandle 70 for helping guide the cog belts 90 a and 90 b aroundrespective sides of the handle 70. The handle 70 and idler wheels mayall be supported by a carriage 98 that is operatively coupled to theguide for sliding movement.

As will be appreciated, linear (sliding) or rotational movement of thehandle 70 results in rotation of the angular sensors 94 a and 94 b. Forexample, sliding the handle 70 to the left in FIG. 7 results in rotationof both angular sensors 94 a and 94 b which rotation can be converted tobrake signals and fed to the actuators as described previously.Meanwhile, rotation of the handle 70 either clockwise orcounterclockwise also results in rotation of the angular sensors 94 aand 94 b such that left and right side brake signals can be generated.Although the linear position of the handle 70 could be determined solelyby analyzing the signals produced by the angular sensors 94 a and 94 b,a linear sensor could also be provided to measure such movementdirectly. By comparing the signals from each angular sensor 94 a and 94b to each other (and/or a linear sensor if so equipped), differentialemergency brake signals can be generated. As will be appreciated,redundant sensors could be provided in place of or in addition to thevarious idler wheels and/or pulleys.

Turning now to FIGS. 8A-8C and 9, another embodiment of a brake inputdevice is illustrated and generally referred to by reference numeral100. In this embodiment, the brake input device 100 includes a pair ofpedals 104 a and 104 b. The pedals 104 a and 104 b may be made to looklike aircraft rudder pedals or the like. The pedals may be activated bya pilot's feet as conventional pedals, or may be manual controlsintended to be activated by a pilot's hands. In this regard, the pedalscan be ergonomically shaped for grasping by a pilot's hand or hands, andcan be configured to be pushed or pulled to initiate and/or increasebraking.

Each pedal 104 a and 104 b is operatively coupled to sensors 108 (FIG.9) that sense movement of each pedal 104 a and 104 b (e.g., depression).For example, each pedal could be coupled to an angular sensor formeasuring rotation about respective pivot points P of each pedal as apedal is depressed. Alternatively, a linear displacement sensor could beoperatively coupled to each pedal so as to measure depression as afunction of the movement of the free end of the pedal, for example. Thesensors 108 convert movement of the pedal into respective brake signalsthat are then fed to the actuators as previously described to implementemergency braking/steering.

In the position of FIG. 8A, the brake input device 100 is deactivated,and no signal is being sent to the actuators (e.g. neither pedal 104 aor 104 b is depressed). In FIG. 8B, the left pedal 104 a is partiallydepressed while the right pedal 104 b remains in the position of FIG.8A. This corresponds to a differential braking mode wherein the lefthand brakes of the aircraft are activated to a greater extent than theright hand brakes resulting in the aircraft rotating towards the leftduring braking. Of course, the right side pedal could be depressedslightly or even more so than the left pedal, the latter instanceresulting in rotation of the aircraft to the right.

In FIG. 8C, both pedals 104 a and 104 b are fully depressed, and aparking brake latch 110 is positioned above the pedals 104 a and 104 bto maintain both pedals in the parking brake position. As will beappreciated, a switch associated with the parking brake latch 110 (seeFIG. 2) can indicate to the BCSU when the parking brake latch 110 is inthe parking brake applied position.

Turning now to FIGS. 10 and 11, another exemplary embodiment isillustrated. In this embodiment, a handle 140 having a grip 144 to begrasped by a pilot's hand is provided. The handle 140 is supported forpivoting movement in a vertical plane at pivot P1, The handle 140 canpivot between a horizontal position and more vertical position, forexample, as shown. Movement of the handle 140 between such positions canbe detected by a suitable sensor (not shown), such as a rotary motionsensor, and can be used to generate a braking magnitude signal in amanner similar to that set forth above in connection with the otherembodiments. As will be appreciated, the greater the angle .phi. thegreater the magnitude of overall braking. A lock/release button 148 canbe provided for locking the handle in a brake applied position (e.g.,parking brake).

Turning to FIG. 11, it will be appreciated that the handle 140 also isconfigured to pivot in a second plane (e.g., the horizontal plane inFIG. 11). To this end, a second pivot point P2 permits pivoting of thehandle 140 to the left and right as shown to generate a signalcorresponding to the distribution of the overall braking level betweenleft and right brake assemblies. Moving the handle 140 left correspondswith more left hand braking and less righthand braking resulting in theaircraft steering towards the left. Moving the handle 140 to the rightcorresponds with more righthand braking and less left hand brakingresulting in the aircraft steering towards the right. As will beappreciated, the greater the angle θ the greater the braking bias to agiven side.

During operation, a pilot will pull upward on the handle 140 pivotingthe handle 140 through an angle φ in order to apply the brakes. To applydifferential braking, the pilot can then pivot the handle left or rightwhile maintaining the handle at an angle φ.

With reference to FIG. 17, functional diagram 1700 is shown depictingthe embodiment shown in FIGS. 10 and 11. Handle 144 is shown with rotarysensors 1702 and 1704.

In FIG. 12, another exemplary embodiment of the brake input device isillustrated. In this embodiment, the brake input device is a T-handle200 that is slideable fore and aft to control overall braking level, androtatable about a central axis A to control differential braking. TheT-handle 200 includes a leg 204 that can be connected to suitablesensors via a carriage such as previously described or via other means.A handle portion 208 is supported by the leg 204 for manipulation by apilot. A lock button 212 is provided on a side of the handle portion 204for locking the handle 200 in a parking brake position.

With reference to FIG. 13, the T-handle 200 is illustrated in a varietyof positions corresponding to varying levels of overall braking and/ordifferential braking. The T-handle 200 is slideable forward to theemergency mode as shown. The T-handle 200 also is rotatable clockwiseand counterclockwise (as shown about axis A in FIG. 12) to controldifferential braking. For example, rotating the handle 204 clockwise cancorrespond to more right hand braking and less left hand braking thuscausing an aircraft to tend to steer towards the right. Conversely,rotation of the handle 204 counterclockwise can correspond to more lefthand braking and less right hand braking thus causing an aircraft totend to steer leftward. As will be appreciated, the lock button 212 canbe depressed to lock the handle in a park position corresponding to fulloverall braking level in the emergency mode, for example.

Turning to FIGS. 14-16, yet another exemplary brake input device isillustrated. In this embodiment, the brake input device is in the formof a cantilevered handle 220 that is pivotable in a vertical plane abouta pivot point P for indicating overall braking level, and also isrotatable about differential pivot point P_(D) for indicatingdifferential braking offset as shown in FIG. 15. For example, in FIG. 14the greater the angle φ the greater the overall braking level. In FIG.15, the greater the angle θ, either positive or negative as the case maybe, the greater the braking bias to a given side. For example, if thehandle 220 is rotated clockwise (e.g., negative θ) more braking may beapplied to the right hand brakes and less to the left hand brakes whileif the handle 220 is rotated counterclockwise (e.g., positive θ) morebraking may be applied to the left hand brakes and less to the righthand brakes.

To illustrate this concept, FIG. 16 shows the overall braking level anddifferential braking offset generated by the handle 220 in variouspositions. As will be appreciated, the concept illustrated in FIG. 16generally is applicable to other embodiments described above. The fourpositions of the handle 220 on the left hand side of the graph under“Equal LH/RH Braking” relate to varying degrees of overall braking. Thepositions range from about zero degrees psi to about 45 degrees psicorrespond to zero overall braking and maximum overall braking,respectively. The intermediate positions illustrate overall brakingamounts between zero and the maximum. Thus, the handle is shown atvarying degrees of the angle φ, with a greater angle corresponding to agreater level of overall braking as described above.

On the right side of the graph under “Differential Braking” the handle220 is shown in five different positions H1-H5, each positioncorresponding to a different angle θ. The line L_(θ) represents theangle θ at the various positions. Positive values of angle θ correspondsto more left hand braking and less right hand braking, while negativevalues of angle θ corresponds to more right hand braking and less lefthand braking. Meanwhile, lines L_(LH) and L_(RH) represent therespective left hand and right hand braking values at a give angle θ.

Beginning with position H1, the handle is rotated counterclockwisetowards the left thereby increasing the angle θ to a positive value.Accordingly, L_(LH) indicates an increased amount of left hand brakingwhile L_(RH) indicates a decreased amount of right hand braking.

At position H2, the handle 220 is rotated counterclockwise back towardsthe right causing angle θ to decrease in value towards zero andeventually go negative. Thus, L_(LH) trends back towards zero whileL_(RH) increases. At position H3, L_(RH) is positive while L_(LH) isnegative thereby indicating more right hand braking and less left handbraking.

At position H3, the handle 220 is rotated counterclockwise back towardsthe left but remains at a negative angle θ until position H4. Thus,L_(RH) increases at lesser rate while L_(LH) decreases at a lesser rate.At position H4, the handle 220 is rotated counterclockwise to a positiveangle θ and thus L_(RH) returns to zero and then goes negative, whileL_(LH) goes positive.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (components, assemblies,devices, compositions, etc.), the terms (including a reference to a“means”) used to describe such elements are intended to correspond,unless otherwise indicated, to any element which performs the specifiedfunction of the described element (i.e., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary embodiment or embodiments of the invention. In addition, whilea particular feature of the invention may have been described above withrespect to only one or more of several illustrated embodiments, suchfeature may be combined with one or more other features of the otherembodiments, as may be desired and advantageous for any given orparticular application.

In addition, the invention is considered to reside in all workablecombinations of features herein disclosed, whether initially claimed incombination or not and whether or not disclosed in the same embodiment.

What is claimed is:
 1. An emergency brake input device for providingemergency braking signals to at least two brake assemblies, the devicecomprising an input member movable in a first direction corresponding toa braking magnitude and movable in a second direction corresponding to arelative distribution of the braking magnitude between first and secondbrake signals for the control of the at least two brake assemblies,whereby the first and second brake signals can be modulated duringemergency braking so as to apply differential braking to separate wheelsof an aircraft wherein the input member is pivotable about a first pointlocated on the input member in a first plane to indicate brakingmagnitude and pivotable about a second point located on the input memberin a second plane to indicate relative distribution of the brakingmagnitude, wherein the second point is displaced from the first pointalong a length of the input member, wherein a first rotary motion sensorand a second rotary motion sensor generate a brake signal, wherein theinput member comprises a handle and a lock/release button, wherein thefirst point is located at a first end of the handle and the lock/releasebutton is located at a second end of the handle, wherein thelock/release button is operable to lock the handle in a brake appliedposition and to release the handle from the brake applied position. 2.An emergency brake input device as set forth in claim 1, wherein thebrake signal is an electric signal.
 3. The emergency brake input deviceas set forth in claim 1, wherein the brake applied position correspondsto a maximum magnitude of braking.
 4. The emergency brake input deviceas set forth in claim 1, wherein the lock/release button is a a parkingbrake lock for locking the input member in a parking brake position. 5.The emergency brake input device as set forth in claim 4, furthercomprising a parking brake sensor for sensing when the input device isin a parking brake mode and for generating a signal in response thereto.6. An aircraft braking system comprising at least one brake assembly forbraking a wheel of an aircraft, the braking assembly including at leastone actuator for effecting a braking action in response to a brakingsignal provided thereto, and the brake input device as set forth inclaim 1 for providing the braking signal to the brake actuator.